In the central nervous system (CNS) the transmission of stimuli takes place by the interaction of a neurotransmitter, which is sent out by a neuron, with a neuroreceptor.
L-glutamic acid, the most commonly occurring neurotransmitter in the CNS, plays a critical role in a large number of physiological processes. The glutamate-dependent stimulus receptors are divided into two main groups. The first main group forms ligand-controlled ion channels. The metabotropic glutamate receptors (mGluR) form the second main group and, furthermore, belong to the family of G-protein-coupled receptors.
At present, eight different members of these mGluR are known and of these some even have sub-types. On the basis of structural parameters, the different influences on the synthesis of secondary metabolites and the different affinity to low-molecular weight chemical compounds, these eight receptors can be sub-divided into three sub-groups: mGluR1 and mGluR5 belong to group I, mGluR2 and mGluR3 belong to group II and mGluR4, mGluR6, mGluR7 and mGluR8 belong to group III.
Ligands of metabotropic glutamate receptors belonging to the group II can be used for the treatment or prevention of acute and/or chronic neurological disorders such as psychosis, schizophrenia, Alzheimer""s disease, cognitive disorders and memory deficits.
The present invention relates to compounds of the general formula I 
These compounds have been discovered to act as metabotropic glutamate receptor antagonists and accordingly are useful for the treatment of a range of neurological disorders, including psychosis, schizophrenia, Alzheimer""s and other cognitive and memory disorders.
Objects of the present invention are compounds of formula I and their pharmaceutically acceptable salts per se and as pharmaceutically active substances, their manufacture, medicaments based on a compound in accordance with the invention and their production, as well as the use of the compounds in accordance with the invention in the control or prevention of neurologial disorders, and, respectively, for the production of corresponding medicaments.
The present invention relates to compounds of formula I 
wherein
X is a single bond or an ethynediyl group, wherein,
In case X is a single bond, R1 is halogen or phenyl which is optionally substituted with halogen, lower alkyl, halo-lower alkyl, lower alkoxy, halo-lower alkoxy, or cyano;
In case X is an ethynediyl group, R1 is phenyl, optionally substituted with halogen, lower alkyl, halo-lower alkyl, lower cycloalkyl, lower alkoxy or halo-lower alkoxy;
R2 is halogen; hydroxy; lower alkyl; lower halo-alkyl; lower alkoxy; hydroxymethyl; hydroxyethoxy; lower alkoxy-(ethoxy)n (n=1 to 4); lower alkoxymethyl; cyanomethoxy; morpholine-4-yl; thiomorpholine-4-yl; 1-oxothiomorpholine-4-yl; 1,1-dioxothiomorpholine-4-yl; 4-oxo-piperidine-1-yl; 4-alkoxy-piperidine-1-yl; 4-hydroxy-piperidine-1-yl; 4-hydroxyethoxy-piperidine-1-yl; 4-lower alkyl-piperazine-1-yl; alkoxycarbonyl; 2-dialkylamino-ethylsulfanyl-; N,N-bis lower alkylamino lower alkyl; carbamoylmethyl; alkylsulfonyl; lower alkoxycarbonyl-lower alkyl; alkylcarboxy-lower alkyl; carboxy-lower alkyl; alkoxycarbonylmethylsulfanyl; carboxymethylsulfanyl; 1,4-dioxa-8-aza-spiro[4.5]dec-8-yl; carboxy-lower alkoxy; cyano-lower alkyl; 2,3-dihydroxy-lower alkoxy; carbamoylmethoxy; 2-oxo-[1,3]-dioxolan-4-yl-lower alkoxy; (2-hydroxy-lower alkyl)-lower alkyl amino; hydroxycarbamoyl-lower alkoxy; 2,2-dimethyl-tetrahydro-[1,3]dioxolo[4,5c]-pyrrol-5-yl; lower alkoxy-carbamoyl-lower alkoxy; 3R-hydroxy-pyrrolidin-1-yl; 3,4-dihydroxy-pyrrolidin-1-yl; 2-oxo-oxazolidin-3-yl; lower alkyl-carbamoylmethoxy; or aminocarbamoyl-lower alkoxy;
R3 is a 5 or 6 membered aryl or heteroaryl which are optionally substituted by halogen; cyano; nitro; azido; hydroxy; carboxy; morpholine-4-carbonyl; carbamoyl; thiocarbamoyl; N-hydroxycarbamoyl; trimethylsilyl-ethynyl; or lower alkyl; lower alkoxy; halo-lower alkyl; 4-lower alkyl-piperazine-1-carbonyl; lower alkylcarbamoyl which are optionally substituted by amino, lower alkylamino, acylamino, oxo, hydroxy, lower alkoxy, lower alkylthio, or carboxy which is optionally esterified or amidated; or an optionally substituted five-membered aromatic heterocycle, which may be optionally substituted by amino, lower alkylamino, acylamino, oxo, hydroxy, lower alkoxy, lower alkylthio, or carboxy which is optionally esterified or amidated, or lower alkyl which is optionally substituted by halogen, amino, lower alkylamino, acylamino, hydroxy, lower alkoxy, lower alkylthio, acyloxy, lower alkenoyl, lower alkylsulfinyl, lower alkylsulfonyl, cycloalkylsulfinyl, cycloalkylsulfonyl, hydroxyimino, alkoxyimino, carboxy which is optionally esterified or amidated, lower alkenyl, oxo, cyano, carbamoyloxy, sulfamoyl which is optionally substituted by lower alkyl, or amidino which is optionally substituted by lower alkyl, xe2x80x94C(NRRxe2x80x2)xe2x95x90NRxe2x80x3 (where R, Rxe2x80x2 and Rxe2x80x3 are hydrogen or lower alkyl)
and their pharmaceutically acceptable addition salts.
It has surprisingly been found that the compounds of formula I are metabotropic glutamate receptor antagonists. Compounds of formula I are distinguished by valuable therapeutic properties.
The compounds of the present invention can be used for the treatment or prevention of acute and/or chronic neurological disorders such as psychosis, schizophrenia, Alzheimer""s disease, cognitive disorders and memory deficits.
Other treatable indications in this connection are restricted brain function caused by bypass operations or transplants, poor blood supply to the brain, spinal cord injuries, head injuries, hypoxia caused by pregnancy, cardiac arrest and hypoglycaemia. Further treatable indications are chronic and acute pain, Huntington""s chorea, amyotrophic lateral scherosis (ALS), dementia caused by AIDS, eye injuries, retinopathy, indiopathic parkinsonism or parkinsonism caused by medicaments as well as conditions which lead tn glutamate-deficiency functions, such as e.g. muscle spasms, convulsions, migraine, urinary incontinence, nicotine addiction, opiate addiction, anxiety, vomiting, dyskinesia and depressions.
Objects of the present invention are compounds of formula I and their pharmaceutically acceptable salts per se and as pharmaceutically active substances, their manufacture, medicaments based on a compound in accordance with the invention and their production, as well as the use of the compounds in accordance with the invention in the control or prevention of illness of the aforementioned kind, and, respectively, for the production of corresponding medicaments.
Preferred compounds of formula I in the scope of the present invention are those in which R3 is phenyl substituted in meta position by cyano; halogen; or imidazolyl which is optionally substituted by lower alky or methylsulfanyl; 1,2,3-triazolyl; 1,2,4-triazolyl; or isoxazolyl which is optionally substituted by lower alkyl.
The following are examples of such compounds:
3-(8-Chloro-4-oxo-7-phenylethynyl-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl)-benzonitrile
3-[8-(4-Methyl-piperazin-1-yl)-4-oxo-7-phenylethynyl-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl]-benzonitrile;
3-(8-Chloro-4-oxo-7-phenyl-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl)-benzonitrile;
[4-(3-Cyano-phenyl)-2-oxo-8-phenylethynyl-2,3-dihydro-1H-benzo[b][1,4]diazepin-7-ylsulfanyl]-acetic acid methyl ester;
2-[4-(3-Cyano-phenyl)-2-oxo-8-phenylethynyl-2,3-dihydro-1H-benzo[b][1,4]diazepin-7-yl]-acetamide;
3-(8-Methoxy-4-oxo-7-phenylethynyl-4,5-dihydro-3H-benzo[b][1,4]diazepin-2yl)-benzonitrile
3-(8-Cyanomethyl-4-oxo-7-phenylethynyl-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl)-benzonitrile;
4-(3-Iodo-phenyl)-7-(2-methoxy-ethoxy)-8-phenylethynyl-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
4-(3-Imidazol-1-yl-phenyl)-7-(2-methoxy-ethoxy)-8-phenylethynyl-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
[RS]-3-[4-Oxo-8-(2-oxo-[1,3]dioxolan-4-ylmethoxy)-7-phenylethynyl-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl]-benzonitrile;
7-Hydroxymethyl-4-(3-imidazol-1-yl-phenyl)-8-phenylethynyl-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
[4-(3-Imidazol-1-yl-phenyl)-2-oxo-8-phenylethynyl-2,3-dihydro-1H-benzo[b][1,4]diazepin-7-yloxy]-acetonitrile;
8-(4-Fluoro-phenylethynyl)-7-hydroxymethyl-4-(3-imidazol-1-yl-phenyl)-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
7-(2-Hydroxy-ethoxy)-4-(3-imidazol-1-yl-phenyl)-8-phenylethynyl-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(4-Fluoro-phenyl)-7-[4-(2-hydroxy-ethoxy)-piperidin-1-yl]-4-(3-imidazol-1-yl-phenyl)-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(4-Fluoro-phenyl)-7-hydroxy-4-(3-imidazol-1-yl-phenyl)-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(2-Fluoro-phenyl)-7-methoxy-4-[3-(2-methyl-imidazol-1-yl)-phenyl]-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(2-Fluoro-phenyl)-7-hydroxy-4-(3-[1,2,3]triazol-1-yl-phenyl)-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(2-Fluoro-phenyl)-7-hydroxy-4-[3-(2-methyl-imidazol-1-yl)-phenyl]-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(2-Fluoro-phenyl)-7-hydroxy-4-[3-(2-methylsulfanyl-imidazol-1-yl)-phenyl]-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(2,5-Difluoro-phenyl)-7-methoxy-4-(3-[1,2,3]triazol-1-yl-phenyl)-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
8-(2-Fluoro-phenyl)-7-hydroxy-4-[3-(3-methyl-isoxazol-5-yl)-phenyl]-1,3-dihydro-benzo[b][1,4]diazepin-2-one;
3-[7-(2,5-Difluoro-phenyl)-8-hydroxy-4-oxo-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl]-benzonitrile;
8-(4-Fluoro-phenylethynyl)-7-hydroxy-4-(3-imidazol-1-yl-phenyl)-1,3-dihydro-benzo[b][1,4]diazepin-2-one; and
8-(4-Fluoro-phenylethynyl)-7-hydroxy-4-(3-[1,2,3]triazol-1-yl-phenyl)-1,3-dihydro-benzo[b][1,4]diazepin-2-one.
Compounds of formula 1, wherein R3 is thiophenyl, preferably thiophen-2-yl, which is optionally substituted by cyano or halogen; or R3 is pyridinyl, preferably pyridin-4-yl, which is optionally substituted in 2-position by cyano or halogen, or wherein R3 is thiazolyl which is optionally substituted in 2-position with imidazolyl or 4-methylimidazolyl, are also preferred.
The following compounds are particularly preferred:
5-[7-(2-Fluoro-phenyl)-8-methoxy-4-oxo-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl]-thiophene-2-carbonitrile;
2-[7-(2-Fluoro-phenyl)-8-hydroxy-4-oxo-4,5-dihydro-1H-benzo[b ][1,4]diazepin-2-yl]-thiophene-3-carbonitrile;
4-[7-(2-Fluoro-phenyl)-8-methoxy-4-oxo-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl]-pyridine-2-carbonitrile;
4-[7-(4-Fluoro-phenyl)-8-hydroxy-4-oxo-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl]-pyridine-2-carbonitrile;
4-[7-(2-Fluoro-phenyl)-8-hydroxy-4-oxo-4,5-dihydro-3H-benzo[b][1,4]diazepin-2-yl]-pyridine-2-carbonitrile; and
8-(2-Fluoro-phenyl)-4-[2-(4-methyl-imidazol-1-yl)-thiazol-4-yl]-1,3-dihydro-benzo[b][1,4]diazepin-2-one.
All tautomeric forms of the compounds of the invention are also embraced herewith.
The term xe2x80x9clower alkylxe2x80x9d used in the present description denotes straight-chain or branched saturated hydrocarbon residues with 1-7 carbon atoms, preferably with 1-4 carbon atoms, such as methyl, ethyl, n-propyl, i-propyl and the like.
The term xe2x80x9clower cycloalkylxe2x80x9d used in the present description denotes cyclic saturated hydrocarbon residues with 3-5 carbon atoms, preferably with 3 carbon atoms, such as cyclopropyl.
The term xe2x80x9clower alkoxyxe2x80x9d denotes a lower alkyl residue in the sense of the foregoing definition bonded via an oxygen atom.
The term xe2x80x9chalogenxe2x80x9d embraces fluorine, chlorine, bromine and iodine.
The term xe2x80x9c5 or 6 membered aryl or heteroarylxe2x80x9d embraces phenyl, thiophenyl, pyridine, partially hydrated pyridine.
The expression xe2x80x9cfive-membered aromatic heterocyclexe2x80x9d embraces, furan, thiazol, imidazol, pyrazol, 1,3-thiazol, 1,3-oxazol, 1,2-oxazol, 1,2-thiazol, 1,2,3-triazol, 1,2,4-triazol, 1,2,4-oxadiazol, 1,2,3-oxadiazol, 1,2,4-thiadiazol, 1,2,3-thiadiazol and tetrazol.
The compounds of formula I and their pharmaceutically acceptable salts can be manufactured according to the following methods: 
According to scheme A, compounds of formula I, in which X, R1, R2 and R3 are as described above, can be prepared from compounds of formula II via an acylation-deprotection-cyclization sequence:
For example reacting compounds of formula II with a dioxinone IV, in which R3 is as described above, in an inert solvent such as toluene or xylene at elevated temperatures, preferably between 80xc2x0 C. and 160xc2x0 C. gives rise to compounds of formula III.
Alternatively, compounds of formula III can also be prepared by for example reaction of a compound of formula II with a xcex2-ketoester (formula IVa), in which R3 is as described above using the same conditions as described for the reaction with the dioxinones.
Afterwards, cleaving the BOC protecting group in compounds of formula III and concomitant cyclization of the deprotected compound yields the desired compounds of formula I. Any other suitable amino protecting group, such as e.g. Fmoc or benzyloxycarbonyl (Z), can be alternatively used instead of the BOC group.
The deprotection-cyclization step can be carried out by treating the compounds of formula III with for example a Bronsted acid such as trifluoroacetic acid in an inert solvent such as dichloromethane (DCM). The reaction is preferably carried out at temperatures between 0xc2x0 C. and 50xc2x0 C. It may be advantageous to use also anisole or 1,3-dimethoxybenzene as a carbocation scavenger in the reaction mixture. 
According to scheme B, compounds of formula II in which R1 is as described above for compounds where X is a single bond and R2 is as described above, can be prepared by different routes depending on the nature of R2 from the iodo-compounds of formula V, in which R2 is as described above. As shown in scheme B, the key steps are coupling reactions of Suzuki-and Stille-type in presence or absence of carbonmonoxide. The exact conditions for the respective compounds of formula II can be found in the experimental part.
Compounds of formula V, in which R2 is as described above, can be prepared by different routes depending on the individual residue R2: 
As shown in scheme C, compounds of formula Va, in which R2 is lower alkyl, halogen or alkoxycarbonyl, can be prepared from the known compounds of formula XI by iodination and subsequent protection of the synthetic intermediates with formula XII.
The iodination step can be carried out by for example using iodine monochloride in acetic acid in the presence of sodium acetate. The reaction can be for example carried out at temperatures between 20xc2x0 C. and 80xc2x0 C.
The protection of the amino function can be achieved by for example reacting compounds of formula XII with di-tert.-butyl-carbonate in the presence of a base such as cesium carbonate. The reaction can be carried out in polar solvents such as acetone or butanone and the like at temperatures between 20xc2x0 C. and 60xc2x0 C.
As shown in scheme D, compounds of formula Vb and Vc, in which R2 is attached via a sulfur- or nitrogen-atom (R2 represents for example morpholin-4-yl; thiomorpholino-4-yl; dialkylamino; carboxymethylsulfanyl etc), respectively, can be prepared from the intermediate XIII by a nucleophilic substitution reaction with the respective amines or mercaptanes in the presence of a suitable base. 
The reaction is preferably carried out in a polar, aprotic solvent such as dimethyl formamide, N-methyl-pyrrolidone or dimethyl sulfoxide and the like. The base can be selected from the sterically hindered amines such as Hxc3xcnig""s base, alkoxides such as sodium methoxide and tert.-butoxide, or hydrides such as sodium hydride. The reaction can be performed at temperatures between 20xc2x0 C. and 110xc2x0 C., depending on the individual compounds to be synthesized.
Compounds of formula Vd in which R2 is attached via an oxygen atom (R2 represents for example lower alkoxy, lower halo-alkoxy, lower cyclo-alkoxy, lower alkoxy-lower alkoxy; etc.) can be prepared as for example shown in scheme E: 
by a nucleophilic aromatic substitution reaction with the respective alcohol in the presence of a suitable base and subsequent protection of the amino function. The base can be selected from the class of Bronsted bases such as potassium hydroxide and the like. The reaction is preferably carried out in a polar, aprotic solvent such as dimethyl formamide, N-methyl-pyrrolidone or dimethyl sulfoxide and the like at temperatures between 20xc2x0 C. and 100xc2x0 C.
The protection of the amino function can be achieved by for example reacting compounds of formula XV with di-tert.-butoxy carbonate in the presence of a base such as cesium carbonate. The reaction can be carried out in polar solvents such as acetone or butanone and the like at temperatures between 20xc2x0 C. and 60xc2x0 C.
Another method to achieve this protection step is to transform first the amino function in a compound with formula XV into an isocyanate by reaction with phosgene or a phosgene equivalent in the presence of a suitable base, which is then treated with tert.-butyl-alcohol to give the desired compounds of formula Vd.
Another suitable method to achieve this protection step is to transform first the amino function in a compound with formula XV into the corresponding di-Boc compound by reaction with excess di-tert.-butoxy carbonate in the presence of 4-dimethylaminopyridine (DMAP), which is then treated with 2eq. TFA in dichloromethane to give the desired compounds of formula Vd.
This reversal of steps, i.e. performing first the nucleophilic aromatic substitution on the key intermediate XIV and second protection of the amino-function as shown in synthetic scheme E can also be applied to those compounds with the formula Vb and Vc (synthetic scheme D).
Yet another method of preparing compounds of the formula Vd is using the O-allyl compound XIX and perfoming a deallylation-alkylation sequence as outlined in scheme E. The deallylation is preferably carried out by transition-metal catalyzed isomerisation, e.g. in the presence of Rhodium(I)-salts like for example Wilkinson""s catalyst [(PPh3)3RhCl] or Palladium(II)-salts such as [(PPh3)2PdCl2], followed by aqueous acid hydrolysis of the resulting vinyl ether. An example for this procedure can be found in J. Org. Chem. 1973, 38, 3224. The alkylation of the phenol XX to the desired compound of the formula Vd can be carried out with electrophilic reagents of the formula Rxe2x80x94X, in which R has the meaning of lower alkyl, lower alkenyl, alkyl acetate or benzyl and X represents a leaving group, for example iodide, bromide, methanesulfonate or tolylsulfonate, in a suitable solvent in the presence of a base. The reaction is preferably carried out in polar, aprotic solvents, for example chlorinated solvents such as dichloromethane, chloroform or dichloroethane, or amides, for example dimethylformamide, dimethylacetamide and N-methyl-pyrrolidone, or sulfoxides, for example dimethyl sulfoxide. The base can be selected from the sterically hindered amines such as Hxc3xcnig""s base, alkoxides such as sodium methoxide and tert.-butoxide, hydrides such as sodium hydride, hydroxides such as potassium hydroxide, carbonates such as potassium carbonate or hydrogen carbonates such as potassium hydrogen carbonate. The reaction can be performed at temperatures between xe2x88x9220xc2x0 C. and 80xc2x0 C., depending on the individual compounds to be synthesized. For the synthesis of an O-tert.-butyl compound with the formula Vd the phenol XX can be treated with DMF-di-tert.-butylacetal in toluene or benzene at 80xc2x0 C. as described in Synthesis 1983, 135.
According to synthetic scheme F, 
compounds of formula Ve and Vf in which R2is attached via a carbon atom (R2represents for example lower alkyloxy-carbonyl-methyl; cyano-methyl, etc.) can be prepared from compound XIII or XIV by for example reaction with a malonic acid ester or -half-ester in the presence of a base followed by the removal of one of the alkyl carboxylates via decarboxylation. The exact reaction conditions vary with the identity of the individual compounds and are described in the examples.
The key intermediates XIII and XIV can be prepared as already described in scheme C.
For the one-carbon-moiety bearing compounds of the formula Vh to VI, the synthesis starts from known methyl 3-amino-4-nitrobenzoate. Standard iodination as described in synthetic scheme C leads to the iodide XXI, which in turn can be protected with the Boc-group. The reduction of the methyl ester can for example be performed by treatment with lithium borohydride, sodium borohydride or diisobutylaluminumhydride in an aprotic solvent like for example THF, ether or toluene. The presence of an alcohol such as methanol, ethanol or isopropanol can be advantegous. The reduction is preferably carried out at temperatures between xe2x88x9220xc2x0 C. and 0xc2x0 C. Further functionalization, like for example conversion into a chloride (Vk), of the resulting benzylic alcohol Vh follows standard procedures known to someone skilled in the art. The exact reaction conditions vary with the identity of the individual compounds and are described in the examples. 
According to scheme G, compounds of formula II in which R1 is as described above for compounds where X is an ethynediyl group can be prepared by different routes from the iodo-compounds V, depending on the nature of R1 and R2As shown in scheme G, the transformation can for example be carried out
a) by directly attaching the R1-alkynediyl-substituent to a compound of formula V via a Sonogashira-type coupling followed by the reduction of the nitro group or
b) by two stepwise Sonogashira-type couplings, in which first trimethylsilyl-acetylene is coupled to a compound of formula V to yield, after deprotection with sodium hydroxide in methanol, the intermediate XVIII which then can be transformed via a second Sonogashira-type coupling with the appropriate reactant R1xe2x80x94I, R1xe2x80x94Br or R1xe2x80x94OSO2CF3and reduction of the nitro group to the desired compounds of formula II.
The exact conditions for the respective compounds can be found in the experimental part. 
According to Scheme H, the dioxinones and xcex2-keto esters building blocks with the formula IV and IVa can be prepared by methods known to someone skilled in the art from the corresponding carboxylic acid derivatives R3xe2x80x94COR, i.e. free acids, methyl or ethyl esters and acid chlorides. The exact conditions for the corresponding compounds can be found in the experimental part.
Another synthetic route to prepare compounds of formula I in which R1, R2and X have the meaning as described above and R3is a carbamide of formula C(O)NR4R5, in which R4 and R5 is hydrogen, lower alkyl or R4 and R5 together form a morpholino-residue or a N-methyl-piperazine, is outlined in scheme I: 
The exact conditions for the respective compounds can be found in the experimental part.
The pharmaceutically acceptable salts can be manufactured readily according to methods known per se and taking into consideration the nature of the compound to be converted into a salt. Inorganic or organic acids such as, for example, hydrochloric acid, hydrobromic acid, sulphuric acid, nitric acid, phosphoric acid or citric acid, formic acid, fumaric acid, maleic acid, acetic acid, succinic acid, tartaric acid, methanesulphonic acid, p-toluenesulphonic acid and the like are suitable for the formation of pharmaceutically acceptable salts of basic compounds of formula I. The compounds of formula I and their pharmaceutically acceptable salts are metabotropic glutamate receptor antagonists and can be used for the treatment or prevention of acute and/or chronic neurological disorders, such as psychosis, schizophrenia, Alzheimer""s disease, cognitive disorders and memory deficits. Other treatable indications are restricted brain function caused by bypass operations or transplants, poor blood supply to the brain, spinal cord injuries, head injuries, hypoxia caused by pregnancy, cardiac arrest and hypoglycaemia. Further treatable indications are acute and chronic pain, Huntington""s chorea, ALS, dementia caused by AIDS, eye injuries, retinopathy, idiopathic parkinsonism or parkinsonism caused by medicaments as well as conditions which lead to glutamate-deficient functions, such as e.g. muscle spasms, convulsions, migraine, urinary incontinence, nicotine addiction, psychoses, opiate addiction, anxiety, vomiting, dyskinesia and depression.
The compounds of formula I and pharmaceutically acceptable salts thereof can be used as medicaments, e.g. in the form of pharmaceutical preparations. The pharmaceutical preparations can be administered orally, e.g. in the form of tablets, coated tablets, dragxc3xa9es, hard and soft gelatine capsules, solutions, emulsions or suspensions. However, the administration can also be effected rectally, e.g. in the form of suppositories, or parenterally, e.g. in the form of injection solutions.
The compounds of formula I and pharmaceutically acceptable salts thereof can be processed with pharmaceutically inert, inorganic or organic carriers for the production of pharmaceutical preparations. Lactose, corn starch or derivatives thereof, talc, stearic acid or its salts and the like can be used, for example, as such carriers for tablets, coated tablets, dragxc3xa9es and hard gelatine capsules. Suitable carriers for soft gelatine capsules are, for example, vegetable oils, waxes, fats, semi-solid and liquid polyols and the like; depending on the nature of the active substance no carriers are, however, usually required in the case of soft gelatine capsules. Suitable carriers for the production of solutions and syrups are, for example, water, polyols, sucrose, invert sugar, glucose and the like. Adjuvants, such as alcohols, polyols, glycerol, vegetable oils and the like, can be used for aqueous injection solutions of water-soluble salts of compounds of formula I, but as a rule are not necessary. Suitable carriers for suppositories are, for example, natural or hardened oils, waxes, fats, semi-liquid or liquid polyols and the like.
In addition, the pharmaceutical preparations can contain preservatives, solubilizers, stabilizers, wetting agents, emulsifiers, sweeteners, colorants, flavorants, salts for varying the osmotic pressure, buffers, masking agents or antioxidants. They can also contain still other therapeutically valuable substances.
As mentioned earlier, medicaments containing a compound of formula I or a pharmaceutically acceptable salt thereof and a therapeutically inert excipient are also an object of the present invention, as is a process for the production of such medicaments which comprises bringing one or more compounds of formula I or pharmaceutically acceptable salts thereof and, if desired, one or more other therapeutically valuable substances into a galenical dosage form together with one or more therapeutically inert carriers.
The dosage can vary within wide limits and will, of course, be fitted to the individual requirements in each particular case. In general, the effective dosage for oral or parenteral administration is between 0.01-20 mg/kg/day, with a dosage of 0.1-10 mg/kg/day being preferred for all of the indications described. The daily dosage for an adult human being weighing 70 kg accordingly lies between 0.7-1400 mg per day, preferably between 7 and 700 mg per day.
The present invention relates also to the use of compounds of formula I and of pharmaceutically acceptable salts thereof for the production of medicaments, especially for the control or prevention of acute and/or chronic neurological disorders of the aforementioned kind.
The compounds of the present invention are group II mGlu receptor antagonists. The compounds show activities, as measured in the assay described below, of 50 xcexcM or less, typically 3 xcexcM or less, and ideally of 0.5 xcexcM or less. In the table below are described some specific pKi values of preferred compounds.
[3H]-LY354740 Binding on mGlu2 Transfected CHO Cell Membranes
Transfection and Cell Culture
cDNA encoding the rat mGlu2 receptor protein in pBluescript II was obtained from Prof. S. Nakanishi (Kyoto, Japan), and subcloned into the eukaryotic expression vector pcDNA I-amp from Invitrogen (NV Leek, The Netherlands). This vector construct (pcD1mGR2) was co-transfected with a psvNeo plasmid encoding the gene for neomycin resistance, into CHO cells by a modified calcium phosphate method described by Chen and Okayama (1988). The cells were maintained in Dulbecco""s Modified Eagle medium with reduced L-glutamine (2 mM final concentration) and 10% dialysed foetal calf serum from Gibco BRL (Basel, Switzerland). Selection was made in the presence of G-418 (1000 ug/ml final). Clones were identified by reverse transcription of 5 xcexcg total RNA, followed by PCR using mGlu2 receptor specific primers 5xe2x80x2-atcactgcttgggtttctggcactg-3xe2x80x2 and 5xe2x80x2-agcatcactgtgggtggcataggagc-3xe2x80x2 in 60 mM Tris HCl (pH 10), 15 mM (NH4)2SO4, 2 mM MgCl2, 25 units/ml Taq Polymerase with 30 cycles annealing at 60xc2x0 C. for 1 min., extention at 72xc2x0 C. for 30 s, and 1min. 95xc2x0 C.
Membrane Preparation
Cells, cultured as above, were harvested and washed three times with cold PBS and frozen at xe2x88x9280xc2x0 C. The pellet was resuspended in cold 20 mM HEPES-NaOH buffer containing 10 mM EDTA (pH 7.4), and homogenised with a polytron (Kinematica, AG, Littau, Switzerland) for 10 s at 10 000 rpm. After centrifugation for 30 min. at 4xc2x0 C., the pellet was washed once with the same buffer, and once with cold 20 mM HEPES-NaOH buffer containing 0.1 mM EDTA, (pH 7.4). Protein content was measured using the Pierce method (Socochim, Lausanne, Switzerland) using bovine serum albumin as standard.
[3H]-LY354740 Binding
After thawing, the membranes were resuspended in cold 50 mM Tris-HCI buffer containing 2 mM MgCl2 and 2 mM CaCl2, (pH 7) (binding buffer). The final concentration of the membranes in the assays was 25 xcexcg protein/ml. Inhibition experiments were performed with membranes incubated with 10 nM [3H]-LY354740 at room temperature, for 1 hour, in presence of various concentrations of the compound to be tested. Following the incubations, membranes were filtered onto Whatmann GF/C glass fiber filters and washed 5 times with cold binding buffer. Non specific binding was measured in the presence of 10 xcexcM DCG IV. After transfer of the filters into plastic vials containing 10 ml of Ultima-gold scintillation fluid (Packard, Zxc3xcrich, Switzerland), the radioactivity was measured by liquid scintillation in a Tri-Carb 2500 TR counter (Packard, Zxc3xcrich, Switzerland).
Data analysis
The inhibition curves were fitted with a four parameter logistic equation giving IC50 values, and Hill coefficients.